1. Field of the Invention
The present invention relates generally to a machining simulation system used for confirming a numerical control (NC) program and, more particularly, to the display of a cross-section and a plane of a three-dimensional shape.
2. Related Background Art
Machining simulation is know in which a tool working a material is displayed as an animation picture. This machining simulation exhibits such advantages that: it is possible to quickly easily confirm a mistake in an NC program and conditions, good or bad, of machining procedures before actual machining is performed; a machining deterioration and a machine impingement can be prevented; dry running is unnecessary; and a machine operation rate can be improved.
FIG. 1 is a block diagram showing one example of a conventional machining simulation system. An operator proceeds with a check of an NC program by inputting a command from a keyboard 1, confirming a system operation by seeing characters and graphics of a display device 2 and inputting the next command as needed. The input from the keyboard 1 is interpreted as a command, and an internal arithmetic operation is performed in accordance therewith. The display is effected by changing contents of a character memory 3 and a graphic memory 4. All these operations are executed by a CPU 6 in conformity with the program stored in a ROM 5. On this occasion, an operation storage area within a RAM 7 is employed. Prepared further is a read command for inputting the NC program. The NC program is inputted from a medium 9 through an I/O (input/output) device 8 and transferred to the NC program storage area within the RAM 7.
Before executing the machining simulation, data representing a material shape and data representing a tool shape are developed in a material shape storage area and a tool shape storage area within the RAM 7. The material shape and the tool shape are specified based on the NC program or in accordance with the operator's inputs from the keyboard 1. For displaying an animation picture, there are effected step-by-step reading from the NC program storage area and interpretations thereof. A tool position per unit time is calculated. Next, when the tool shape is put in the tool position, an intruding portion into the material shape is calculated, thereby changing the material shape. This material shape is read, and a variety of converting processes are carried out. The material shape is depicted on the graphic memory 4, thus displaying a projected plane and a cross-section thereof. The material appears to be machined by consecutively executing these processes at short time intervals.
The conventional machining simulation system described above presents the following problems. It is important to shorten the display time intervals by speeding up the processes associated with the change of the material shape and the graphic memory depiction in order to effectively display the animation picture. If the time interval increases, the motion becomes rough, and fine motions can not be seen, or the time required for the machining simulation increases. Further, the processing time is reduced with a decline of the resolution of the material shape. However, the details of the shape can not be seen. In any case, it follows that those are contrary to the object of the machining simulation.
A method has been proposed of simply reducing the processing time by using a parallel computer and a high-speed CPU having a high arithmetic capability. The system itself, however, becomes very expensive. It is therefore difficult to incorporate the machining simulation system in a NC system and an automatic programming system for wide use at production sites to improve productivity.
Under such circumstances, it is difficult to display the high-speed animation picture especially in the three-dimensional display. A machining simulation system is desired which is capable of displaying the animation picture without using an expensive CPU.